A teenager who planned to blow up his school will be charged with attempted aggravated murder after six bombs were found in his bedroom, a US prosecutor said on Saturday.

Grant Acord, 17, planned to attack his school in Oregon in a plot "forged and inspired" by a 1999 mass shooting at a high school in Columbine, Colorado, said the Benton county district attorney, John Haroldson.

Acord will be charged as an adult and also faces six counts of manufacturing and possessing a destructive device. He was taken to a juvenile jail on Thursday night after police received a tipoff that he was making a bomb to blow up West Albany high school.

Investigators found the six bombs in a hidden compartment in his bedroom, Haroldson said, along with written plans, a checklist and a timeline for the attack. They found pipe bombs, Molotov cocktails, a drain cleaner bomb and a napalm bomb, Haroldson said. Police found no explosives during a search of the school.

Haroldson did not say on which date Acord allegedly planned to attack the school, but said it would be included in court paperwork to be filed this week.

Haroldson said he was not aware Acord had any major problems, such as a suspension, at school.

"In any case that you have a young person that in essence plans to take a video game approach to killing people at school, you have to take a close look at the mental health issues," he said. "And the process will certainly provide for that once he's represented by counsel."

The district attorney said it did not appear that the teenager was targeting a specific person or group of people. He said Acord would probably be charged on Tuesday.

"I can't say enough about how lucky we are that there was an intervention," Haroldson said. "When I look at the evidence in the case, I shudder to think of what could have happened here."